It depends if you have a "sealed for life" transmission. I know the E38's did. The early E32 transmissions did not and required you to change the oil regularly, however, I'm not sure about the later E32 models when the 740 came out. Still, on the E38 models, it's still a good idea to change the oil once in a few hundred thousand km's especially when you start to exhibit transmissions shifting/whining problems.